L&S ElectricEASA AR100 Accreditation

EASA AR100 Accredited

EASA AR100 Accreditation

• First company in Wisconsin, Minnesota, and Michigan to earn accreditation.• First company to obtain

accreditation for multiple locations• Providing our customers the

assurance of maintaining efficiency and overall reliability

DC Motor On-Site Maintenance Practices Related to Commutation

V - Ring

Commutation Construction

BONDED COMMUTATOR

RESI-GLASS BINDER

STEEL HUB

INSULATION

SEGMENTS

Bonded

Commutation Construction

L&S ElectricDC Electric Motor Repair

Motor Nameplate

• The motor nameplate is a very important part of the repair process• The information from the nameplate is entered onto the job card

that follows the motor throughout the shop• This data is also entered into our data base and is stored so it

can be obtained at a later date if needed• The Model and Serial numbers are

very important when it comes to ordering specific parts for motors

Job Card

• A final output shaft TIR is taken prior to run out

Job Card

Output Shaft TIR Keyseat Check

• All output shafts (if shaft rotates) are checked to insure they are in tolerance with reference to the EASA AR 100 Permissible Shaft Extension Runout document

Shafts .1875 to 1.625 = .002 TIR MaxShafts 1.625 to 6.500 = .003 TIR Max

• Keyseats are checked using a calipers and new non-plated key stock• Keyseats should be true and

accommodate keys to a tap fitWidth of keyseat .188 to .750 (+.002/-.000)Width of keyseat .750 to 1.500 (+.003/-.000)

Grease Tubes Removed

• On motors that have grease tube extensions the tubes are removed• This insures the grease holes in the bearing housing are able to

be cleaned properly• Generally all grease tubes are

replaced with new tubes

Brushes Removed

Brush Springs Inspected

• Brushes are inspected for abnormal wear, fraying shunts, burned shunts• Brush spring pressure is measured prior to removing the

springs. Brush spring pressure should be between 4-6 PSI for most motors• Brush springs are inspected for stretched coils, and any signs of

damage

Bearing Cap and Housing Bolts Removed

Housings Carefully Removed

Housings are match marked to the field frame prior to removal to insure they are installed in the correct orientation when it is assembled

Contaminants

• The motor is also examined for contaminant intrusion• Contaminants such as paper stock as seen

here suggest possible compromised air ducting, plugged filters, or flooding condition

Bearing Grease Inspected

• Before the grease in the bearing housing is removed the volume and condition is inspected. The grease is examined for contaminants or signs of electrical discharge and noted on the job card• The grease in the bearings themselves

is also examined• This inspection can be beneficial the

motor because if a condition exists preventative measures can be added to the motor during the repair process to remedy the problem

Bearing Inspection

Bearings are inspected for:• Grease quantity and condition• Visible cage defects• Signs of frosting or fluting from stray voltage discharge

Bearing Removal

• Bearings are removed using a bearing puller• Shaft center savers are used to preserve the condition of the

centers during bearing removal

Commutator End Bearing Removed

Some encoder/tach shafts need to be removed prior to pulling bearing to avoid damage to the shaft

Shaft Grounding

Shaft grounding devices are often utilized where circulating currents are known to be present

Ceramic Ball Bearings

• Ceramic ball bearings are used to protect bearings from circulating shaft currents• The best combination for a motor is insulation of the Opposite

Drive End bearing (in various fashions) and a shaft grounding device on the Drive End of the motor

Micrometers Set to Calibrated Standard Prior to Checking Fits

Instruments are calibrated on a scheduled basis

Bearing Journals are Measured

• Bearing journals are measured during disassembly and the sizes are documented on the job card

• The EASA fit tolerance chart is used to determine if the sizes are within tolerance

• If a journal does not fall within the tolerance and is undersize, it can be metal sprayed and machined back to within tolerance

Output Shaft and Keyway Checked

• Output shaft extension diameters checked with micrometers to insure they are in tolerance with reference to the EASA Shaft Extension Diameter Tolerance Table in the AR100. If the shaft extension is worn and out of tolerance the shaft can be welded and re-machined• Shaft diameter .1875 to 1.5000

= +0.000/-0.0005• Shaft diameter 1.5000 to 6.500

= +0.000/-0.001• The keyway is checked using

standard non-plated key stock. Keyways should be true and accommodate standard non-plated key stock to a tap fit

Brush Rigging Marked and Removed for Cleaning

• The Brush Rigging is reference marked to the housing before removal• It is inspected for and damage and noted on the job card

Excess Grease Wiped Prior to Measuring Housing Bores

Housings Checked Using Inside micrometers

• Bearing bores are measured using a micrometer• The bearing bore size is documented on the job card• EASA Bearing Fit Tolerance tables are used to determine if

housing bearing bores are within tolerance• If the bearing bore is oversize it can

be bored, sleeved and re-machined back to within tolerance

Insulation Resistance Testing Performed on All Wound Components

• A megohmmeter is used to check the insulation resistance at disassembly• Meg-ohm readings are documented on the job card• Thermostats, heaters and other temperature devices are also

checked during disassembly and recorded on the job card

AC Voltage Drop Test

• Shunt Fields are voltage drop tested by applying 120 volts AC to the field leads• The voltage between each coil is

measured and should be with +/- 5% of the calculated average• Add the measured voltages for

each coil and the sum should be equal to the input voltage

Interpoles Tested

Interpoles are tested by using both a high frequency tester and are also tested using a surge tester

High Frequency Bar to Bar: Testing Armatures

• Using a High Frequency Bar to Bar Tester the armature is tested for any shorts or opens• The filming on commutator surface is also examined.• A chocolate brown color

under the brushes is an ideal filming color

Washing Components

All components that can be are washed with a mild detergent soap and water

Components Drying

Components are dried in an oven at 220 °F until completely dry

Armature Mounted in Lathe

• Bearing journals indicated in to under .001” (As close to zero TIR as possible)

• Armature is checked with a megohmmeter prior to resurfacing• Armature wrapped in

plastic to prevent copper trimmings from entering coil section

Commutator Resurfacing in Lathe

• The commutator is turned so it is concentric with both bearing journals

• A Resurfaced commutator shall have an indicated runout of less that .001”

• Bar to Bar deviation shall be no more than .0002”

• A resurfaced commutator should have a finish of 40-70 microns

Polishing Commutator after Turning

A non-metallic abrasive cloth is used to polish the commutator

Resurfaced Commutator

Mica Under Cutter Set Up and Ready

Undercutting Mica Between Commutator Bars

• Under cutter during operation• Depth of undercut to be 1 to 1.5 times the width of the Mica slot

Deburring BetweenCommutator Bars

• After undercutting the Mica slots, the edges of the commutator bars are deburred to provide a clean smooth edge on each side of the bars.

• The Mica slots are inspected to insure no copper or high Mica is left between the bars

• The armature is checked with a megohmmeter after this step

Final Indicator Run Out Check

A final indicator runout check is done before the armature is removed from the lathe

Bar to Bar Test

A high frequency bar to bar test is performed before it is removed from the lathe to insure there are no shorts or opens present

Dynamically Balancing

• All rotating components receive a two plane ISO G1.0 grade dynamic balance in a calibrated balance stand• Component are balanced to the G1.0 Specification to insure the

assembled motor with perform at the Verso Paper specified vibration limits when test run

Starting Assembly Process

• Prior to assembly all components are checked with a megohmmeter to insure insulation resistance is acceptable• Readings at assembly are recorded on the job card• Thermostats, heaters and

other temperature devices are checked again prior to assembly and recorded onthe job card• Each component and all

interior surfaces are painted with a red insulating spray varnish

Bearings and Grease

• SKF or FAG double shielded C3 fit bearings are used• Mobil Polyrex EM grease is used in bearing caps and bearing

housings• Bearings are warmed to 210 ° F by an induction heater equipped

with automatic degaussing for installation• The bearing shield facing the grease

cavity is removed prior to installing the bearing housing• An insulated commutator end bearing

is installed at this time if required• The commutator is also wrapped in

preparation for the bearing housing to be installed

Preparing Housings for Installation

• The bearing housing grease cavity is filled to ½ capacity• The brush boxes are raised to the highest setting to provide

adequate clearance to for assembly• The Brush rigging is then

installed lining up the match marks that were made at disassembly.

Bearing Housings Installation

• The bearing housing is carefully aligned and slid onto the bearing• In some cases as seen here a crane is needed to assist in the

alignment of the rabbet fits

Bolting Bearing Housings

• Once the machined rabbet fits are aligned the bolts are started• A crane is once again sometimes necessary to support the

bearing housing depending on size

Drive End Bearing

• The drive end bearing cap and bearing are installed• If an AEGIS® grounding ring is to be used, a great place to install

it is behind the drive end bearing cap. This keeps it clean and out of harms way.

Drive End Housing Ready To Go

Installing Drive End Bearing Housing

• The drive end bearing housing is installed• Care is taken to insure all match marks are aligned so that all

openings are in the correct orientation

Bearing Cap Bolts Installed

Checking Commutator TIR Prior to Test Run

The commutator is checked with an dial indicator to insure overall commutator run out is under .001” after motor is assembled

Setting Brush Box Height

• Each brush box is set to the proper height from the commutator• Normally this height is set at .081” from the commutator surface• Once the box is set to the proper height it is torqued

to the correct value for the bolt used

Getting Ready to Seat Brushes

• A strip of garnet paper is cut to fit the commutator and applied to the commutator• The brushes are all installed but the shunts are not connected at

this point

Seating Brushes

• The shaft is rotated several times to sand the brush bevels to match the contour of the commutator• Each brush is checked to insure at least 90% of the brush has

been seated prior to removing the garnet paper• Once the garnet paper is removed

the motor is blown out and the brush shunts are attached and torqued

Setting Neutral and Checking Interpole to Brush Holder Polarity

• The Neutral position is set and the brush rigging is locked in position using the locking bolts• Checking Interpole to Brush Holder polarity• 20-40 Volts AC is applied to adjacent brush posts• The voltage measured on A1 and

A2 should be less than applied voltage to confirm correct polarity• If voltage measured on A1 and

A2 is higher than applied, all leads going to the brush holder must be moved to adjacent posts

Final Shaft Run Out

A final output shaft TIR is taken prior to run out

Motor “No Load” Test Run

Each motor is no load test run at full voltage in both directionsRunning in both directions:• Insures a good neutral

setting by running the same speed in each direction • Allows the technician to

fully seat the brushes by using a light seating stone• Vibration analysis and

bearing temperatures are also taken during this time

Test Panel Report

• Vibration analysis is taken to insure vibration levels are within EASA or customer’s specific acceptable parameters • Vibration analysis is also

taken to insure no bearing defects are present• The vibration spectrum is

printed for each motor and kept with the job file• A test report from the

panel is generated and stored and a copy is printed kept with the job file

“Full Load” Test Run

• Once the motor has been run on the test panel at no load and the brushes are fully seated in both directions the motor is run at full load.• This test is done to insure the motor performs as designed under

load• The load test report is

printed and kept with the job file

Motor is Painted and Prepared for Delivery

• All nameplates, encoder pilots, shafts and openings are masked off prior to painting• New inspection windows and new gaskets are installed on all

covers and junction box• All grease tubes (if applicable) are filled 100% with Mobil Polyrex

EM prior to installation• A light rust inhibitor is applied to

the output shaft• Exterior of motor is painted a

color specified by a Verso paper representative• Grease fittings with caps and grease

reliefs are installed

Motor is Painted and Prepared for Delivery

• Repaired motors have a metal tag install to identify the repair facility, job number, date and type of repair• A tag is installed that identifies the bearing manufacturer, part

number and if applicable the Inpro Seal part number for each end of the motor• All motor weighing in access of 20 ponds shall have the weight

prominently stenciled in a highly visible area on the motor• All motors equipped with Drive End roller bearing intended for horizontal application shall be tagged with a Red tag marked “Horizontal Belted Application”• All motors equipped with Drive End roller bearing intended for vertical application shall be tagged with a Yellow tag marked “Vertical Belted Application”

Thank You

We thank you for the opportunityto present this information